The present invention relates generally to apparatus for generating plastic foam, and more specifically to a novel gun-type apparatus which forms part of a non-circulating plastic foam system.
Apparatus of the type described comprises separate sources for the components of the plastic foam, e.g., a polyether and a diisocyanate. The components are separately communicated to a reaction chamber, and the resulting foam is selectively discharged from the chamber so that it can be applied in the manner desired.
The gun-type generating apparatus of the prior art is characterized by the presence of check valves and/or variable flow control valves which are exposed to the atmosphere when the apparatus is not in use. The residue of the plastic foam materials which coats these valves is dried by exposure to air so that the valves can become clogged and inoperative after short periods of use. Consequently, the prior art apparatus must be cleaned frequently in order to assure proper and efficient operation.